Device for anchoring a shoulder prosthesis in a reverse configuration, bone fixing screw and anchoring system

Abstract

A device for anchoring a shoulder prosthesis in a reverse configuration includes a baseplate delimited at the bottom by a first at least partially convex surface, and at the top by a second concave surface, opposite the first surface, and peripherally by a third truncated-cone or cylindrical surface; and a central pin, protruding from the first surface at a first end thereof, and defining an axially pass-through inner duct having at least one main diameter. The central pin has a second free end, opposite the first end. The duct has a helical cavity made in the inner wall delimiting the duct, open towards the inside of the duct and extending along the length of the duct. The inner duct has a secondary diameter smaller than the main diameter, and the helical cavity has a diameter larger than the main diameter of the inner duct.

1 . A device for anchoring a shoulder prosthesis in a reverse configuration, comprising:
 a baseplate delimited at a bottom of the baseplate by a first at least partially convex surface, adapted to interface with a glenoid, at a top of the baseplate by a second concave surface, opposite the first surface, and peripherally by a third truncated-cone or cylindrical surface,   a central pin, protruding from said first surface, having an axially pass-through inner duct having at least one main diameter said central pin having a first end connected to said baseplate and a second free end opposite said first end;   said duct having a helical cavity made in an inner wall of the duct delimiting said duct, the inner wall being open towards an inside of the duct and extending along an entire length of said duct, in such a way as to place in fluid communication the second surface of the baseplate with the second end of said central pin; wherein said inner duct has a secondary diameter smaller than said main diameter and said helical cavity has a diameter greater than the main diameter of the inner duct.   
     
     
         2 . The device according to  claim 1 , wherein said helical cavity has a pitch and profile designed to be coupled with a pitch and profile of a fixing screw that can be screwed into said duct. 
     
     
         3 . The device according to  claim 1 , wherein said baseplate has, at the pin, a central hole passing through and communicating with the duct inside the pin; said first end of said pin being connected to said baseplate and opening externally into said second concave surface through said central hole, while said second end of said central pin is open externally. 
     
     
         4 . The device according to  claim 1 , wherein said inner duct has at least one threaded portion having a pitch and height different from those of the helical cavity, so that it can be coupled with a second threaded screw which may be fitted through said first end of said central pin, adapted to fix a glenosphere. 
     
     
         5 . The device according to  claim 1 , wherein said inner duct has an end portion, placed at the second end of said pin, having a diameter smaller than the main diameter of the duct. 
     
     
         6 . The device according to  claim 1 , wherein a change in diameter of said duct takes place in an intermediate zone between the second surface of the baseplate and the second end of the central pin; said duct having the main greater diameter extending in a portion between the baseplate and said intermediate zone and the secondary smaller diameter extending in the portion between said intermediate zone and the second end of the central pin. 
     
     
         7 . The device according to  claim 1 , wherein said pin has a cylindrical shape and has a corrugated outer surface comprising a plurality of circumferential discharges. 
     
     
         8 . The device according to  claim 1 , wherein said baseplate has at least two peripheral through holes that place said first at least partially convex surface in communication with said second concave surface  22 . 
     
     
         9 . The device according to  claim 1 , wherein said first surface has, at least partially, raised wedge-shaped portions. 
     
     
         10 . A bone fixing screw insertable in the device according to  claim 1  for anchoring a shoulder prosthesis in a reverse configuration, comprising: a cylindrical body, a tip placed at one end of the cylindrical body, a head placed at a second end of the cylindrical body, opposite to the first end, and a thread extending helically along an entire axial extension of said cylindrical body, wherein said head has an outer diameter greater than the outer diameter of said cylindrical body and smaller than the outer diameter of the thread. 
     
     
         11 . The bone fixing screw according to  claim 10 , wherein said head has a cylindrical shape, without protruding portions; said head connecting to said cylindrical body by a tapered portion. 
     
     
         12 . The fixing screw according to  claim 10 , wherein said tip has at least one notch having a cutting edge. 
     
     
         13 . An anchoring system for anchoring a shoulder prosthesis in a reverse configuration comprising an anchoring device and a fixing screw, wherein:
 the anchoring device comprises:
 a baseplate delimited at a bottom of the baseplate by a first at least partially convex surface, adapted to interface with a glenoid, at a top of the baseplate by a second concave surface, opposite the first surface, and peripherally by a third truncated-cone or cylindrical surface, 
 a central pin, protruding from said first surface, having an axially pass-through inner duct having at least one main diameter, said central pin having a first end connected to said baseplate and a second free end opposite said first end; 
 said duct having a helical cavity made in an inner wall of the duct delimiting said duct, the inner wall being open towards an inside of the duct and extending along an entire length of said duct, in such a way as to place in fluid communication the second surface of the baseplate with the second end of said central pin; wherein said inner duct has a secondary diameter smaller than said main diameter and said helical cavity has a diameter greater than the main diameter of the inner duct; and 
   the fixing screw comprises:
 a cylindrical body, a tip placed at one end of the cylindrical body, a head placed at a second end of the cylindrical body, opposite to the first end, and a thread extending helically along an entire axial extension of said cylindrical body, wherein said head has an outer diameter greater than the outer diameter of said cylindrical body and smaller than the outer diameter of the thread. 
   
     
     
         14 . The anchoring system according to  claim 13 , wherein said helical cavity has a pitch, profile and depth designed to be coupled with a pitch, profile and height of the thread of the fixing screw which can be screwed into said duct. 
     
     
         15 . The anchoring system according to  claim 13 , wherein the head of the fixing screw has an outer diameter equal to the secondary diameter of the duct inside the anchoring device. 
     
     
         16 . The anchoring system according to  claim 13 , wherein the outer diameter of the thread of the fixing screw is equal to the diameter of the helical cavity of the anchoring device.